Intervals are the single most results producing exercise that I’ve ever found for boosting your metabolism, helping you burn inches off your body, and giving you a tight, lean, strong shape.

Here’s an excerpt from my latest article in Men’s Fitness showing you how to use intervals for fat loss (Men’s Fitness, Page 114, April 2005).

Interval training is the fitness world’s equivalent of a visit to the in-laws. The shorter and more intense the visit, the better.

An interval is a short period of exercise performed at a given intensity for a specific length of time. Each interval is separated from the next interval by a short rest or lighter activity. There are no strict rules on how long or how intense the interval must be, however, changing the interval length or intensity changes the way your body works and responds to exercise.

Never sacrifice the quality of rest between intervals because this will only reduce the benefits. To succeed with intervals, you must first shake the mindset of traditional continuous cardio training.

No matter where you start with intervals, heed this warning. The high-intensity nature of the exercise can cause muscle soreness you’d associate only with weights, and can cause your legs to feel like j-e-l-l-o.

What most people don’t know is that intervals are the best cardio method for fat loss. Most guys in the gym are hung up on doing excessive amounts of work, but shorter, more intense intervals get the job done better.

Intervals continue to burn calories and fat after the training session, and that’s something you won’t get from slower, longer sessions of cardio. When Canadian researchers compared interval training and long, slow cardio training, it was interval training that was shown to be more effective for fat loss.

Use this workout 3-5 times per week to blast fat.

Start with this beginner protocol:

Warm-up for 5-minutes.

Work for 30 seconds at an 8/10 level of intensity.

Follow that with “active rest” for 90 seconds at a 3/10 level of intensity.

Repeat for 3-8 intervals.

Finish with 15 minutes of traditional cardio for “transition” and cool-down.

As you become accustomed to intervals, progress to the experienced protocol:

Warm-up for 5-10 minutes.

Work at a 9/10 level of intensity for 30 seconds.

Follow that with “active rest” for 60 seconds at a 3/10 level of intensity.